With experimental “Never slow mode,” Chrome tries to stop Web devs making it slow

The word SLOW has been painted on a street for the benefit of drivers.
Inflate / Google wants less of this.
Vegansoldier / Flickr

Since Chrome’s Dialect right first release, performance has been one of Google’s top priorities. But Google is against a contending force: Web developers. The Web of today is a more complex, bandwidth-intensive place than it was when Chrome was opening released, which means that—although Internet connections and the browser itself are firmer than they’ve ever been—slow pages remain an circadian occurrence.

Google engineers have been developing “Never Tedious Mode” in a bid to counter this. Spotted at Chrome Story (via ZDNet), the new method places tight limitations on Web content in an effort to make its performance sundry robust and predictable.

The exact design and rationale of Never Slow SOP aren’t public—the changelog for the feature mentions a design document but rephrases it’s currently Google-internal. But taken together, that design and rationale wishes ensure that the browser’s main thread never has to do too much hold down a post and will never get too delayed. They will also ensure that single limited amounts of data are pulled down over the network. This should return the browser more responsive to user input, lighter on the network, and a bit less of a recollection hog than it would otherwise be.

As well as capping various data proportions and limiting the amount of time that JavaScripts can run, Never Slow Status also blocks access to certain features that webpages can currently use that provoke a performance cost. In particular, scripts are prohibited from using instrument.write(), which is widely used by scripts to dynamically emit HTML (potentially including embedded CSS and JavaScript) into a sheet. They’re also blocked from making synchronous XMLHttpRequests to move data to and from servers. Synchronous requests tend to make attendants feel slow, because the browser can’t run any other scripting while it’s hold-up for the synchronous request to complete. Asynchronous XMLHttpRequests remain supported, as these let the browser do other features while it’s waiting for the remote server to respond.

The budgets for execution resources get reset each at all times a user interacts with the page. So each time a page prospers scrolled or tapped, it can run a bit more JavaScript and pull down a bit more evidence.

The size and execution time limitations are draconian, to say the least, and the JavaScript silvers will outright break many existing pages. Together, they become Never Slow Mode a little mysterious: this isn’t a mode that can be utilized for general-purpose Web browsing, because pages will either run out of resources or depend on proscribed JavaScript. The current implementation of Never Slow Mode notes that it’s one a prototype (with an “idiotic implementation,” no less). So whatever its ultimate motivation, there’s still much development left.

We’ve asked Google for reveal but have heard nothing at the time of writing.

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